Numerous on-chip voltage generating sources have been suggested for both memory and logic applications where the on-chip voltage source is used to generate a reference voltage which is compared against the voltage signal swing internally generated by the memory or logic circuit. These known prior art on-chip circuits essentially operate under the principle that supply and temperature induced voltage variations across the base to emitter junctions of the transistors located in both the integrated circuit and the reference or threshold voltage source can be made to track with each other and thus result in a substantially constant output signal when compared against each other.
However, these prior art techniques still are susceptible to certain types of process and electrical variations between the on-chip integrated circuit and its on-chip voltage source. Due to these variations it is difficult to insure that the threshold or reference voltage is maintained exactly intermediate to the signal swing associated with the logic or memory circuit. This limitation necessitated that noise tolerance threshold levels be increased in order to assure the generation of error free output signals from the integrated circuit. An increase in the noise threshold level increases power requirements, reduces densities and decreases operating speeds.
It is therefore an object of the present invention to provide an on-chip integrated circuit and an on-chip voltage reference or threshold source that operate at faster speeds, lower power, higher densities and lower noise threshold levels.
Another object of the present invention is to provide an integrated circuit capable of operating at reduced noise threshold levels and which is less sensitive to process variations such as beta, sheet resistivity and mask alignments and to electrical variations such as input signal changes.
A further object of the present invention is to provide an on-chip integrated circuit and associated on-chip voltage reference or threshold circuit which is capable of operating at lower noise threshold levels despite AC and DC impedance variations.